The first time you see them, they come charging at you like colossi – armoured up in shoulder pads and helmets for a game of American football. The next time, they might have stepped off a Harlem street corner in 1961, in leather jackets, jeans and long silky hair, looking like the Ronettes’ harder sisters. Then they’re clubland vamps, dancing to Rihanna in slinky cocktail dresses so freshly shoplifted they still have their security tags. Or just in cornrows and tracksuit pants…

The young heroines of Girlhood are perplexing shape-shifters, defying any attempts to read this new French film as a straightforward social document. If you want to know just how black teenage girls look and behave in the Paris banlieue estates these days, then Girlhood effectively says: “All of the above and none of them.”

Céline Sciamma’s stylish, assertively female-centric feature has been causing a stir in France since its premiere in Cannes last May, not least because it’s that rarest phenomenon, a French film that features an almost exclusively black cast and, what’s more, one in which all the main players are young women.

I didn’t feel I was making a film about black women but with black women – it’s not the same

Céline Sciamma

Two of them are sitting with me at lunch in a boutique hotel near the eastern edge of Paris, a stone’s throw from the towers and walkways of the cités (housing estates) of Bagnolet, where the film was partly shot, and yet, given the hotel’s Philippe Starck swankiness, a world away. Girlhood’s leads are Karidja Touré, now 21, and Assa Sylla, 18, both non-professionals chosen from 300 scouted in a painstaking process of street casting.

They make their debut as members of a four-strong girl gang; their characters are rawhide-tough on the outside, complex and vulnerable within, and bound by ties of friendship made deeply moving by these novice actress’ confident, charismatic performances.

But while Girlhood ostensibly smacks of social-realism reportage, anyone expecting its stars to be the proverbial Real Thing should check their prejudices. To be pedantic, only two of the quartet, Lindsay Karamoh and Mariétou Touré, are from the banlieue as such (the latter is from up the road in Bagnolet), while Touré is from Paris’s 15th arrondissement, around Montparnasse, and Sylla from multiracial Barbès, in the 18th. These two are not that much like the tough-shelled personas adopted by their screen characters: they’re personable, thoughtful, turned out with impeccable chic and radiating self-possessed beauty.

When they signed up for Girlhood, Touré admits: “We didn’t know anything about cinema. I don’t think my life has changed that much but lots of little things have been added to it – photo sessions, interviews, TV. I really enjoy all that.”

Scouted while out with friends at the Foire du Trône funfair, Touré has spent much of the last year promoting the film and doing fashion shoots for the likes of Vanity Fair and Teen Vogue; earlier this year, she was nominated best female newcomer in France’s César awards. Then there’s the travel, accompanying the film to festivals – Toronto, San Sebastian, Dubai… “We’ve pretty much been round the world several times,” says Sylla.

In Girlhood – the French title Bande de filles means Girl Gang – Sylla, the youngest of the quartet, plays alpha femme Lady. She’s the more animated of the duo, with a characterful, raucous rasp in her voice (both are speaking French today, although Touré has confidently handled Q&As interviews in English). “I’m completely the opposite of Lady,” Sylla says. “I’m not the leader sort at all.”

“She’s really not,” Touré agrees. “On set, she was like our little sister and we were protecting her.”

Touré is more reserved, though hardly as quiet as the film’s Marieme; on screen, it’s Touré’s deeply interiorised melancholy that makes her character so enigmatically compelling. Inducting Marieme into the gang, Lady renames her Vic (for Victory); today, Touré is wearing her Vic pendant from the film, but on a sleek ensemble of grey mohair top, leggings and trainers.

People often expect the quartet to be their screen selves but that’s the viewer’s problem, says Céline Sciamma when we talk later. “It’s a fantasy that people have,” says the director, who is intensely serious and a little academic in manner. “They get asked questions as if they were experts – as if the film were a documentary about its actors.”

Girlhood is fiction, Sciamma stresses. Of course, she has repeatedly been asked what qualifies her, a white arthouse director, to tell a story about this milieu and these women. She replies that she’s familiar with the banlieue world, having grown up, like Karamoh, in the new town of Cergy-Pontoise: “I have a strong sense of having lived on the outskirts – even if I am a middle-class white girl. I didn’t feel I was making a film about black women but with black women – it’s not the same. I’m not saying, ‘I’m going to tell you what it’s like being black in France today’; I just want to give a face to the French youth I’m looking at.”

I just couldn’t relate to French films. I didn’t feel they concerned me

Karidja Touré

Sciamma’s film is the newest addition to the French cycle of banlieue cinema. This tradition of largely realist dramas exploded 20 years ago with Mathieu Kassovitz’s epoch-marking La Haine, an energetically stylised evocation of life in the Paris cités that imported the energies of the new African American wave (Spike Lee, John Singleton, the Hughes brothers et al). Banlieue cinema, casting a spotlight on France’s racial and social tensions – and, above all, depicting life way beyond the familiar milieu of the Left Bank bourgeoisie – was a broad chapel, running from gang movies (the punningly titled Ma 6-T va crack-er – My cité’s gonna crack) to high-school realism (Abdellatif Kechiche’s 2003 debut L’esquive).

These films tended to stress the multi-ethnic makeup of modern France – the three young heroes of La Haine, for example, were north African, black and Jewish. But in opting for an all-black cast, Sciamma was deliberately rejecting what some might have seen as a politically correct approach. “That would have been more comfortable, wouldn’t it?” she says. “But I didn’t want to get into that overworked logic of balance and diversity. In terms of fiction, it’s a blind alley.”

What Sciamma was more interested in was looking at the spaces where her heroines live and the particular codes of behaviour imposed by the architecture of the cités – the desolate open spaces, the long passages that Vic has to walk across under the judgmental eyes of young male groups. “Public space isn’t created for the benefit of women,” says Sciamma, “so it becomes a question of territory. The cités are conceived as self-enclosed districts with a strong identity but they end up becoming islands – spaces linked by walkways that just end up creating barriers.”

As for accuracy, Touré and Sylla vouch for Girlhood being close to their experience. Like the gang, these two have their own stories about shopping with friends and automatically being shadowed by security guards. The same goes for the scene in which Marieme is informed by a teacher that her school grades aren’t good enough for her to graduate to a higher class, even though she’s set on pursuing her education. “It happens to loads of girls,” says Sylla.

“Yes, loads of, let’s say, African girls,” Touré says. “I was really glad that scene was in the script – in fact I was shocked that Céline even knew about that because usually people just say, ‘Oh, you didn’t get good enough grades’ – they always find an excuse. These things really happen but you have to fight and get your bac [baccalauréat].”

The film doesn’t provide any specific information about its heroines’ backgrounds, except to show where they live in their cité. (The cité is the “hood” in the English title, which Sciamma chose; echoes of Richard Linklater’s Boyhood are coincidental, she says, “although people might think it’s a cynical bid for attention”.) We never see the girls’ parents, only Marieme’s tyrannical older brother, and no authority figures apart from her teacher. There are no signs of religion shown either. “I wanted a film with no religion and no police,” says Sciamma. “For me, the pressures on women aren’t to do with religion but with economic and social factors.”

The four leads were all born in France, daughters of immigrants – Karidja Touré’s parents are from the Ivory Coast, Sylla’s are Mauretanian, Karamoh’s Malian and Marietou Touré’s from the Ivory Coast and Zaire. A practising Muslim, Karidja Touré explains that she had a more liberal upbringing than girls who come to Paris from “le bled” (the village or the old country. “My mother never stopped me going out or doing anything, she just gave me advice and it was up to me whether I respected it or not. In Africa, you never raise your voice at your parents. But when I was a girl I could disagree with my father and tell him so.”

When I was little and I wanted to be an actress, I never thought it would be in France

Karidja Touré

While Girlhood isn’t a documentary, you nevertheless feel you’re getting a certain amount of sociological detail. There are hair-raising scenes of girl-gang fights, with two leaders challenging each other to a mano a mano showdown while their supporters cheer them on. “I’ve seen that for real,” says Sylla, “and it’s worse than in the film. I was out with friends and we saw two gangs face off – not just two girls fighting, but gang against gang, using baseball bats and crutches.”

An enthusiastic raconteur, Sylla tells another story about being on the metro near her home and being accosted by a girl who tried to walk off with her phone. She started protesting – then the gang arrived. “Twenty, thirty of them, stacked hair, scarves, makeup, the lot. I was really shocked. But I wouldn’t back down and because I’ve got a big mouth it all came down on me – they were pulling my hair and everything.” She only emerged in one piece, she says, thanks to a bystander – “an African dad” – who pulled her out of the fray. The way Sylla tells it, there’s a difference between banlieue girls proper and those who live in Paris, within the Périphérique ring road: “These are banlieue girls who come into town to do that sort of thing, it’s never Parisian girls,” she says, just as a Manhattan girl might tut-tut the Jersey crowd.

But there are other, more joyous aspects to the girls’ life in the film, like the exuberant dance-off at La Défense business district, a scene that Sciamma admits she ramped up a bit: “You don’t necessarily get 50 girls standing around forming a kind of arena – you might get a dozen. That’s a case of making it ‘bigger than life’,” she says, slipping into English, “making it heroic.” In reality, say her stars, those meets would be more likely to happen around Les Halles or the Gare du Nord. “It’s like what they do in the States with flashmobs. We’ve tried to introduce it in France, but we’re a bit crap,” Touré says with a shrug.

Some sceptics have questioned the authenticity of Girlhood’s language. Where US films about young African Americans often pile on the hood speak and Ebonics, Sciamma’s heroines use the everyday French that Touré and Sylla are speaking today. Touré explains: “When we started, Céline said, ‘I don’t want any LOLs, any MDRs [“mort de rire” or “die laughing”] or any Allô Nabilla.’” The reference is to reality star Nabilla Benattia, who launched the catchphrase “Allô quoi”, in France as instantly recognisable a working-class signifier as the British “Yeah but no but…”

I tell people, for once there’s a film with a 100% black cast, and a poster all over Paris with four black faces on it

Assa Sylla

Otherwise, there’s the faintest scattering of slang – like “Wesh”: “‘Hello’ in racaille,” Touré translates. Racaille means “riff-raff” or, worse, “scum” – as it was generally translated when, following the banlieue riots of 2005, Nicolas Sarkozy notoriously proposed blasting such people off the streets with water cannons. Racaille, more sympathetically, can mean working-class youth, specifically of ethnic backgrounds, but it depends who uses the word. “If we say it,” says Touré, “it’s OK. It’s like if you’re black you can say ‘negro’ and no worries. But if not…”

Since opening in France in October Girlhood has chalked up 300,000 admissions and, thanks to a strategy of screenings at multiplexes outside the Périphérique, reached exactly the audience Sciamma hoped to attract – one strongly composed of young black women. But some commentators, in print and in social media, have complained that Girlhood perpetuates stereotypes of France’s black population, of antisocial teens and aggressive men. But the film’s stars defend it staunchly. Sylla says: “I just tell people, for once there’s a film with a 100% black cast, and you see a poster all over Paris with four black faces on it – that’s got to make you smile.”

Still, Sylla has one misgiving. “There’s one thing I do understand. Some girls have said to me: yes, it’s good, I can see myself in it, but how come none of the girls succeeds in life?”

Touré adds: “People often compare it to Think Like a Man and ask why our film can’t show successful black women.” The movie in question is the glossy 2012 African American romcom starring Gabrielle Union and Kevin Hart. “That’s a film everyone talks about,” Touré says, “because it shows black women who are really magnificent, super-belles.”

If you want to see black women like that on screen, the duo say, or black actors playing bosses rather than cleaners, you have to watch American movies. They’re touching here on a key point about French cinema – the notable scarcity of black presence both on screen and behind the camera. The last two decades in France have seen a significant rise in visibility for talent of north African origin – actors such as Tahar Rahim and Leïla Bekhti, directors such as Rachid Bouchareb and Palme d’Or winner Abdellatif Kechiche. Yet black actors seem fewer and less prominent there, the key exception being Omar Sy, who hit it big in the massively successful comedy The Intouchables and has since embarked on a Hollywood career.

Then there are Thomas N’Gijol and Fabrice Eboué, stars of comedy hits such as Case départ; Senegalese-born Aïssa Maïga, recently seen in Michel Gondry’s Mood Indigo, but not too many more. Behind the screen, there are the Franco-Senegalese auteur Alain Gomis and Haitian-born Djinn Carrénard, whose zero-budget Donoma (2010) launched him as a Cassavetes-esque maverick. Not that these names have travelled widely, presumably because black-themed French cinema is not considered very importable elsewhere.

In any case, Touré and Sylla had given French cinema a wide berth before getting into movies themselves. “I just couldn’t relate to French films,” says Touré. “I didn’t feel they concerned me. When I was little and I wanted to be an actress, I never thought it would be in France – I always thought, ‘Better practise my English so I can be a star in the States.’”

That’s why the pair’s screen interests – outside the odd French film with black stars such as N’Gijol and Eboué – are American, as are their acting aspirations. “I’d love to be in a dance movie like Step Up,” says Sylla, “or a series like Criminal Minds.” They watch US TV shows with black stars, such as Empire and Scandal, while Touré says: “The role model for me and Assa, the American actress we really love, is Lupita Nyong’o – she’s really an icon of African woman.”

Their music is American too. The key musical moment in Girlhood doesn’t claim to offer the hot revelation of whatever’s newest and hippest in the cités. It’s more mainstream than that – Rihanna’s Diamonds, which the gang dance to in a hotel room, in a euphoric set-piece. The singer meets Touré’s and Sylla’s approval totally. When I ask what other music they like, the names come cascading: Chris Brown, Beyoncé, Ariana Grande, Tinashe… and Ed Sheeran. Really? And Justin Bieber. Really really? “Yes, from when I was young,” laughs Touré. “But when I get attached to something I stay faithful.”

Their sartorial tastes, on the other hand, are staunchly European. A committed fashionista, Touré enthuses about what she wore at the Césars ceremony: “Elie Saab, who does long dresses, very pretty, very summery, with the look of natural light. I like Balmain, Chanel… If I were only allowed to go to one shop for the rest of my life, I’d go to Zara.

“And I love bags. Je suis une fille, quoi!”

They’re filles, yes, and their femininity and stylishness emerge to electric effect in the film – except when Marieme/Vic disguises hers by bandaging her breasts tight and wearing baggy, sexless clothes. “That’s what happens in the banlieue,” Touré explains. “Girls in Paris can wear dresses, mini-shorts, whatever. In the banlieue you can’t do that because of the men hanging out, the older brothers – you get classified as a slut. That’s why a lot of girls in the cités walk around in tracksuit pants, and people who see a girl dressed that way on the metro think she’s some little hoodlum. But it’s just to avoid hassles. Sometimes it’s a lot easier to be a boy.”

That sexual slippage is a theme that has continued to fascinate Sciamma. Her 2007 debut Water Lilies depicted teenage sexuality burgeoning among synchronised swimmers, while Tomboy (2011) was about a 10-year-old transgender child. Sciamma, who is gay and out, is fascinated by female identity and its mutations during adolescence, and for her the different looks adopted by Girlhood’s heroines are all about self-discovery: when Vic joins the gang, it’s like being a superhero, she says: “She’s trying on the uniform to see what power it gives her.”

It was also her conscious decision to make a film in which men are background figures. “I do with men here what films usually do with women – I make them archetypes.” She’s turning the tables by objectifying Girlhood’s men, as in the powerful scene in which Vic, at her toughest, tells her boyfriend to undress and turn over so that she can look at his buttocks.

“That’s really what Céline wanted to show in the film,” says Sylla, “domination.” She and Touré crack up with delight. “She’s a feminist.”

Girlhood has put its four young stars in the limelight, but normal life goes on. The other two haven’t made it to the interview today: Karamoh is looking after her baby daughter and Marietou Touré is at work, as a school assistant. As for Karidja Touré, she hopes to carry on acting – she auditioned to play Storm in the next X-Men film, although she didn’t get the role – but she’s continuing her studies, in her second year of working for the “Bac Technicien Supérieur” certificate in management and accountancy. She’s hoping to accompany Girlhood to Senegal in May – all depending on her exam timetable.

Sylla, meanwhile, says she only went to the Girlhood audition to keep some friends company, but it has launched her on a flourishing career. She has parts coming up in two TV series, Falco and the much-exported Spiral, and she has starred in a TV film, Danbé, Head Held High, playing boxing champion Aya Cissoko. It’s going to be screened in Los Angeles, she says.

“Danbé? Really?” Touré whoops with delight. “Ah très bieeeen…!”

“And it’s going to Montreal.”

“Well, c’est normal,” smiles Touré, “because it’s a great film. From start to finish, there’s no way you can watch it and not like it. It’s impossible not to like.”

And the two beam at each other with the kind of pride and solidarity you don’t have to have been in a girl gang to understand.